In the past, lubrication systems utilizing various lubricant storage and releasing materials were well known in the art and commercially acceptable for use in lubricating various apparatus, such as electric motors for instance. The past known lubrication systems utilized commercially available lubricant storage and releasing materials which were composed of various fibrous materials, such as cellulose and synthetic fibers, including wood fibers, cotton fibers, nylon fibers, rayon fibers, glass fibers and the like. One form of past lubricant storing and releasing material, such as an oil impregnated, fibrous wicking material, is commercially available for a lubrication system under the trademark "PERMAWICK" from the Permawick Company of Detroit, Mich. U.S. Pat. No. 2,966,459, issued Dec. 27, 1960 to M. L. Abel for "Material Having Oil Retaining Properties" describes for a lubrication system a lubricant composition composed of cellulose fibers and a lubricating oil. The cellulose fibers which form the oil absorbing part of the wicking material are made from wood fibers and a mixture of paper containing fibers of wood, cotton and the like. U.S. Pat. No. 3,214,375 issued Oct. 26, 1965 to B. Berkeley for "Lubricating Wicking Material" discloses for a lubrication system an oil impregnated storing and releasing material composed of a blend of cellulose and synthetic fibers, such as nylon or rayon fibers. The cellulose fibers are described as being coated at least in part with a coating material of polyvinyl alcohol. U.S. Pat. No. 3,466,244 issued Sept. 9, 1969 to M. L. Able for "Oil-Impregnated Wicking Material" describes for a lubrication system a lubricating oil impregnated storage and releasing material formed of cotton linter fibers. Each of the above three patents is assigned to the Permawick Company, and these patents describe for a lubrication system commercially available Permawick extrudable lubricant storage and releasing material which in each instance has a distinctly fibrous structure. It is believed that at least one of the disadvantageous or undesirable features of these past lubrication systems was that they had a capacity to release only a relatively small or minor portion of the liquid lubricant contained therein.
U.S. Pat. No. 2,960,371 issued Nov. 15, 1960 to L. E. Staak for "Bearing Lubricating Structure" and U.S. Pat. No. 2,979,779 issued Apr. 18, 1961 to L. E. Staak for "Improved Method of Providing a Bearing Lubricating Structure" both describe a lubrication system which comprises an oil impregnated lubrication structure formed by foaming an epoxy or phenolic material in place directly in a bearing housing thereby to form a unitary cellular foam structure in the bearing housing. After the foam is formed in place in the bearing housing, the foam is impregnated with an appropriate lubricating oil.
The use of fibers of glass, asbestos, and the like as fillers for lubricating compounds of a lubrication system is also known in the art. U.S. Pat. No. 2,303,068 issued Nov. 24, 1942 to G. H. Schoembaum for "Lubricant and Preparation Thereof" describes the use of asbestos fibers as a filler to form a viscous lubricating composition. U.S. Pat. No. 3,133,105 issued Dec. 3, 1963 to G. Slayter et al. describes a lubrication system which comprises a silicone fluid lubricant incorporating short lengths of fibrous glass for use at high temperatures.
Various past lubrication systems for bearing structures of apparatus have employed felt feeder wicks. See, for example, U.S. Pat. No. 3,434,765 issued Mar. 25, 1969 to M. L. Abel for "Lubricating Bearing Assembly and Method of Making Same" and U.S. Pat. No. 3,184,272 issued May 18, 1965 to A. J. Ridgway for "Lubricating Means for a Rotatable Device." In this type of lubrication system, it is desirable that the lubricant impregnated or lubricant storing and releasing material release the lubricating oil which it contains at a rate and in an amount sufficient to maintain a steady flow of lubricant through the felt wick to the rotating structure to be lubricated. It is believed that significant problem confronting the art with respect to the past lubrication systems resided in the disadvantageous or undesirable feature that many of the lubricant compositions or extrudable lubricant storing and releasing materials heretofore known, while capable of being extruded or otherwise packed into the bearing structure, were capable of releasing only a relatively small portion of the total amount of lubricating oil contained therein. The smaller the releasable proportion of the liquid lubricant or oil, the shorter the life of the lubrication system, and hence, of the bearing structure itself. Furthermore, the unreleased portion of the lubricant obviously was not available to perform the intended lubricating function.